diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 8cfd55151..4cddb2b0a 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,5 +1,34 @@
 # Contributing to Blockly
 
-Please make pull requests against develop, not master.  If your patch needs to go into master immediately, include a note in your PR.
+Want to contribute? Great!
+- First, read this page (including the small print at the end).
+- Second, please make pull requests against develop, not master. If your patch
+  needs to go into master immediately, include a note in your PR.
 
-For more information, head over to the [Blockly Developers site](https://developers.google.com/blockly/guides/modify/contributing).
+For more information on style guide and other details, head over to the [Blockly Developers site](https://developers.google.com/blockly/guides/modify/contributing).
+
+### Before you contribute
+Before we can use your code, you must sign the
+[Google Individual Contributor License Agreement](https://cla.developers.google.com/about/google-individual)
+(CLA), which you can do online. The CLA is necessary mainly because you own the
+copyright to your changes, even after your contribution becomes part of our
+codebase, so we need your permission to use and distribute your code. We also
+need to be sure of various other things—for instance that you'll tell us if you
+know that your code infringes on other people's patents. You don't have to sign
+the CLA until after you've submitted your code for review and a member has
+approved it, but you must do it before we can put your code into our codebase.
+
+### Larger changes
+Before you start working on a larger contribution, you should get in touch with
+us first through the issue tracker with your idea so that we can help out and
+possibly guide you. Coordinating up front makes it much easier to avoid
+frustration later on.
+
+### Code reviews
+All submissions, including submissions by project members, require review. We
+use Github pull requests for this purpose.
+
+### The small print
+Contributions made by corporations are covered by a different agreement than
+the one above, the
+[Software Grant and Corporate Contributor License Agreement](https://cla.developers.google.com/about/google-corporate).